1. Field of the Invention
This invention relates to a cooling unit for cooling heat generating electronic elements (components) such as a micro processor and an inverter.
2. Description of the Related Art
JP-U-63-164294 discloses a cooling unit shown in FIGS. 10A and 10B. The cooling unit includes plural cooling fins (herebelow, referred to as fins) 320 disposed on a substrate 300 to which electronic components are joined, and an axial fan 310 for blowing cooling air toward the fins 320.
The inventors of the present invention have examined a radiation (cooling) capacity of the cooling unit described above. As a result, it was founded that a temperature at the generally central portion of the substrate 300 was higher than those at the other portions, i.e., a so-called hot-spot was produced at the central portion of the substrate 300. This implies that the cooling unit must adopt a large fan to prevent the hot-spot, resulting in increased size, increased noise, and increased manufacturing cost.